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Model Forum / Radio Controlled / Air Models / February 2004



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End soldered cells, disassembly?

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Wan - 14 Feb 2004 04:06 GMT
I have 4 packs of Sanyo 3000 mAh cells end soldered, 10 in series. I'm
replacing them with Li Poly batteries.

I would like to make them into 6 packs of 6 in series. The problem is
how to melt the solder between the cells without damaging the cells.

Any suggestion will be greatly appreciated.

Wan
daytripper - 14 Feb 2004 04:47 GMT
>I have 4 packs of Sanyo 3000 mAh cells end soldered, 10 in series. I'm
>replacing them with Li Poly batteries.
[quoted text clipped - 3 lines]
>
>Any suggestion will be greatly appreciated.

Best shot: cut them apart first, then use a serious iron, cleaned and well
tinned, to quickly pop the remaining tabs off the poles.

If you have to hold the iron to the pole longer than a couple of seconds, you
ain't doing it right, and what you'll end up with are flashlight batteries...

/daytripper
Wan - 14 Feb 2004 14:03 GMT
> >I have 4 packs of Sanyo 3000 mAh cells end soldered, 10 in series. I'm
> >replacing them with Li Poly batteries.
[quoted text clipped - 11 lines]
>
> /daytripper

Thank you for the suggestion, daytripper. The cells I bought are
tabless NiMH Sanyo 3000 mAh, and I had them soldered together with a
special soldering iron (hammer head tip). The poles of each cell were
tinned then pushed together. They are very closely mated, making it
very difficult to get any cutting instrument between them. Do you
think a razor blade may work?

Best scenario, sell them as is to someone who needs them. Then we'd
both benefit. But the delivery and collection of  $ may be of concern.
Know anyone interested?

Wan
David AMA40795 / KC5UH - 14 Feb 2004 23:22 GMT
If they were soldered properly, then any attempt to separate the cells
will ruin the 2 cells where the separation is attempted!  Usually what
happens is a hole gets ripped in the bottom of the cell if prying.  If
heating, then the cells get so hot they vent the over-pressure.

So basically, use as is or sell to someone who can use the stick.

David

>I have 4 packs of Sanyo 3000 mAh cells end soldered, 10 in series. I'm
>replacing them with Li Poly batteries.
[quoted text clipped - 5 lines]
>
>Wan
Mike Norton - 15 Feb 2004 01:23 GMT
I have assembled end-soldered packs.  I have had pretty good luck by
slightly flexing the joint between the cells.  This will fatigue an ordinary
tin-lead (63/37) solder, and the joint will fall apart.

I don't know how badly this damages the cells, but they looked fine.  I used
them in another pack without problems.  However, the cells were smaller than
yours - Sanyo 500 mAH.

Your mileage may vary.

-- Mike Norton.

> I have 4 packs of Sanyo 3000 mAh cells end soldered, 10 in series. I'm
> replacing them with Li Poly batteries.
[quoted text clipped - 5 lines]
>
> Wan
Wan - 16 Feb 2004 00:02 GMT
> I have assembled end-soldered packs.  I have had pretty good luck by
> slightly flexing the joint between the cells.  This will fatigue an ordinary
[quoted text clipped - 7 lines]
>
> -- Mike Norton.

Mike, Sounds like it could work but I have the electrical solder. I
don't know  it's composition of tin and lead.

Still, I should try it on cheap alkaline C cells first before I ruin
NiMH cells. Also as you know my 3000 mAH sub C cells are of greater
diameter and may require more leverage to flex?

Wan

> > I have 4 packs of Sanyo 3000 mAh cells end soldered, 10 in series. I'm
> > replacing them with Li Poly batteries.
[quoted text clipped - 5 lines]
> >
> > Wan
Mike Norton - 16 Feb 2004 02:31 GMT
If it is Radio Shack electrical solder, it is close to what I used.

My cells were NiCd, not NiMH.  In either case, I don't think alkaline cells
are a good mechanical substitute for deciding whether the process works for
you.

I liked the poster that recommended using a thin blade, using it to roll the
cells back and forth.  I would bet that this fatigues the solder.

> > I have assembled end-soldered packs.  I have had pretty good luck by
> > slightly flexing the joint between the cells.  This will fatigue an ordinary
[quoted text clipped - 26 lines]
> > >
> > > Wan
Pé Reivers - 15 Feb 2004 22:50 GMT
Drain the cells completely, and keep them drained for a while using a short.
Then, using a very thin bladed knife, insert it between the cells, and roll
the cells over the work bench keeping slight pressure on the knife. That way
you may cut the solder without cell damage.
3 out of 4 times it works.

Signature

With Kind Regards,

http://mvvs-nl.com
http://home.wanadoo.nl/pereivers/
___________

> I have 4 packs of Sanyo 3000 mAh cells end soldered, 10 in series. I'm
> replacing them with Li Poly batteries.
[quoted text clipped - 5 lines]
>
> Wan
Wan - 16 Feb 2004 07:21 GMT
> Drain the cells completely, and keep them drained for a while using a short.
> Then, using a very thin bladed knife, insert it between the cells, and roll
[quoted text clipped - 6 lines]
> http://mvvs-nl.com
> http://home.wanadoo.nl/pereivers/

Pé, I finally see what you look like when I clicked onto your web
site. The photo is of you, is it not?

I appreciate your idea of rolling a thin blade between the cells. This
may be done without undue stress to the negative pole, the  bottom of
the cell. I will try your method on cheap end-soldered cells before
attempting on the NiMH packs. 3 out 4 times leaves me about 30 out 40,
in turn leaving me about 5 packs of 6 in series.

I could drain the whole battery pack by connecting a 12 V automobile
lamp. Or must I drain each cell?

Another question is, will draining the cells completely damage the
NiMH cells as it does to Li Poly cells?

Thanks,
Wan
>  ___________
>
[quoted text clipped - 7 lines]
> >
> > Wan
Pé Reivers - 16 Feb 2004 21:08 GMT
NiMH is no different, and may be drained completely. Dont do that with LiPo
though, unless clad in armour, and in the open :-)
A lamp over the pack is good enough. If one cell is severely different and
runs the risk of reverse charging, the pack was no good anyway, and not
worth saving but cel by cell.
The last bit can be accomplished by twisting the cells, and the join will
fal apart.
The draining is required to reduce the high short current that may occur.

Yes, that me, though my hair grows white quite fast now. So much to do, and
so little time.

Signature

With Kind Regards,

http://mvvs-nl.com
http://home.wanadoo.nl/pereivers/
___________

> > Drain the cells completely, and keep them drained for a while using a short.
> > Then, using a very thin bladed knife, insert it between the cells, and roll
[quoted text clipped - 35 lines]
> > >
> > > Wan
Simply Secret - 19 Feb 2004 23:21 GMT
Put the pack in the freezer, after it's really cold a sharp rap on a
the edge of the workbench will snap the batteries appart. Just try it,
it  works.

>NiMH is no different, and may be drained completely. Dont do that with LiPo
>though, unless clad in armour, and in the open :-)
[quoted text clipped - 7 lines]
>Yes, that me, though my hair grows white quite fast now. So much to do, and
>so little time.
Wan - 20 Feb 2004 02:25 GMT
> Put the pack in the freezer, after it's really cold a sharp rap on a
> the edge of the workbench will snap the batteries appart. Just try it,
> it  works.

It sounds so simple. Hmm... I ought to give it a try. As it is, the
batteries will just be wasted since I've gone Li poly.

> >NiMH is no different, and may be drained completely. Dont do that with LiPo
> >though, unless clad in armour, and in the open :-)
[quoted text clipped - 7 lines]
> >Yes, that me, though my hair grows white quite fast now. So much to do, and
> >so little time.

Yeah, Pé. So many things to do and so little time. Can you invent a
time machine? Off topic. Well, what the heck, enjoy! But thanks for
your suggestions.
 
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